Trailer hitch

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Dawud

New Member
Aug 23, 2009
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Prescott, Arizona
After all the parts fetching and the first tack welding I just realized something. I don't have a clue how to attach it to the seat post. This is going to be a pusher trailer. Any ideas? Pictures would be greatly appreciated. Thank you
 

geeksquid

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Feb 14, 2008
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After all the parts fetching and the first tack welding I just realized something. I don't have a clue how to attach it to the seat post. This is going to be a pusher trailer. Any ideas? Pictures would be greatly appreciated. Thank you
There is more than one way of doing it, but first of all, it entirely depends on if your trailer is a two wheel or single wheel.
 

deacon

minor bike philosopher
Jan 15, 2008
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north carolina
I made an electric push and attached it at two points down by the wheel to the bike frame. It seemed to work very nice except it has hard to make tight turns. It was very stable though,.
 

Dawud

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Aug 23, 2009
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Prescott, Arizona
There is more than one way of doing it, but first of all, it entirely depends on if your trailer is a two wheel or single wheel.
I was shooting for either a two or four wheeled trailer. The four wheeled trailer would be set for the front two wheels to pivot like an old wagon.

I made an electric push and attached it at two points down by the wheel to the bike frame. It seemed to work very nice except it has hard to make tight turns. It was very stable though,.
How exactly did you hook that one up that low. Tight turning isn't greatly important as this rig will be used for in-between city travel(Approx. 20 miles one way).

Dawud

.trlrl.
 

denbecr

New Member
Oct 21, 2008
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Illinois
On a push trailer with 1 wheel (simplest, lightest, narrowest, cheapest, easiest to build) you want a u-joint type hitch that allows the trailer to turn and go over bumps but not to be able to flop over sideways. You want it to lean only when the bike leans.

electricbicycletrailer.com Open, then click "learn more". Here's the best design I've seen for a seatpost pusher trailer hitch for a single-wheel pusher. It's simple and strong. Like most seatpost hitches, your frame must be small enough for you to reach your pedals when enough seatpost is exposed to accommodate the hitch.

Look at the picture of the hitch at the bottom of the page, then watch the video at the top of the page. He removes the seatpost, inserts it through the hitch, then reinstalls the seatpost into the frame. The hitch is free to rotate on the seatpost to allow the trailer to turn. The hitch needs only a horizontal hingepin so the trailer can lift over bumps.
A quick release seatpost would be best for this hitch.
The seatpost part of the hitch should be made of wood or plastic which could be bored through with a spade bit. Metal would erode the seatpost unless complicated with bushings/bearings/sealed lubrication etc. The ideal substance for the seatpost block would be UHMW (ultra high molecular weight) polyethylene available as industrial surplus offcuts on eBay.

Below is my version of a hitch that works like a u-joint and adapts to a regular upright diamond frame bike or a recumbent. Click twice to enlarge text to legibility. If you have no need to accommodate a recumbent the yellow portion could be one piece. Two pieces are necessary for a recumbent seatback which can't be inserted through the hitch like a seatpost can.

If you insist on 2 or more trailer wheels, any simple hitch will do that flexes in all directions, so the bike can lean independently of the trailer. This could be a piece of tire sidewall wrapped around the seatpost and bolted together, then bolted to the tongue. You could use an air hose quick coupling or one of very many hitches from bike & motorcycle trailer plans you can Google or find with a search of this forum.
 

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Dawud

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Aug 23, 2009
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Alright, I took apart my tack welds and ground it back to just metal stock for the frame. Attached are a few sketches of what I am shooting for now. The upright box on the trailer is the engine while the wire framed area next to it just shows where the sprocket/ belt drive will come off the engine. You have the drive shaft off the engine as well as a centrifugal clutch. The bar on the very back is a jack shaft running to sprockets on the outside of both wheels. The reason the engine is centered between the tires is because it is a heavy engine and I would like to keep as much weight off of the bicycle as possible. the cargo area in front of the tyres is 3.25' by 4'. I still haven't figured out yet how the trailer will hook to the bike, but I figured this will give you all an idea of what I am shooting for. It is mocked up with 20" wheels. The engine weighs 121 lbs.

Regards,
Dawud

.crt.
.trlrl.
 

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Kevlarr

New Member
Jul 22, 2009
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Never built a pusher but something that works good for a pivot is a small U-joint off the steering shaft of a Japanese built vehicle. Go to your local junk yard and look for a Toyota or a Nissan pickup. Cut the steering shaft just above and below the joint. Grind town the splines on the shaft, drill out the splines on the joint, drill out the threads for the keeper bolt and put a small clevis pin in it's place. You'll have a quick release six axis joint for around $5.
 

denbecr

New Member
Oct 21, 2008
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Illinois
Dawud,
Your engine weighs 121 lbs.! What have you got there? a diesel? A Vanguard twin? You tryin' to break the sound barrier?
 

Dawud

New Member
Aug 23, 2009
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Prescott, Arizona
Dawud,
Your engine weighs 121 lbs.! What have you got there? a diesel? A Vanguard twin? You tryin' to break the sound barrier?
Plane, Trains, and Automobiles can keep the sound barrier. You got it right. It is a 10hp Diesel Yanmar clone. Air cooled. I figured I could run a selectable sprocket and either good GREAT fuel economy or I can pull stumps. It runs up to 3600 rpms, but the highest sweet spot is 3000. Aside from fuel and torque we work with what we have. I have had this engine in my garage for the last 4 months. I bought it to build a generator, but then we moved to a solar house and the engine has just been gathering dust.

Dawud

.trlrl.
 
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denbecr

New Member
Oct 21, 2008
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Illinois
That sounds great. I have often pondered obtaining a 5-6 hp diesel, figuring it could work as a 30MPH pusher trailer that could also carry up to 150 lbs. of camping gear and all the extras you want of things like tools, extra fuel, clothing, electronics, camera, groceries, and a laptop or handheld web accessible computer.
I'd attach a very small generator on the engine or in the drivetrain for battery charging, MP3 player, GPS and phone charging, bright lighting, and a tamper alarm. An engine that size could also spare the 90 watts power necessary to feed a 75 W heated jacket and another 15W or so for heated gloves. My recumbent bike and/or my recumbent trike could be fully enclosed by a carbon fiber tubing and coroplast nose and a tubing framed, Lycra covered, body and tail section with a little bubble windshield.
The streamlining coupled with the fuel efficiency of diesel, even when boosting a relatively large load of freight would result in phenomenal MPG. There's a Dutch 1200cc, 100 mph+, touring bike that gets 150 MPG. A 5-6 hp diesel at half the 1200's speed should exceed that 150 MPG considerably. Conversion of the diesel to run on used, filtered cooking oil is relatively easy. Feed yourself and your engine at the same time at fast food restaurants.
The full fairing and heated clothing would enable year round comfortable transportation to anywhere, as long as the roads weren't icy. You'd have the most efficient RV around for lots of long haul adventures.
With 10 hp, you could do the same with a passenger on your tandem bike and all his necessities and conveniences added to a bit larger pusher trailer. Go all the way and bring your dog and a bag of dog food. I'll start tomorrow & have it built in a week! Now click the pig.
 

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Kevlarr

New Member
Jul 22, 2009
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That sounds great. I have often pondered obtaining a 5-6 hp diesel, figuring it could work as a 30MPH pusher trailer that could also carry up to 150 lbs. of camping gear and all you extras you want of things like tools, extra fuel, clothing, electronics, camera, groceries, and a laptop or handheld web accessible computer.
With a 10hp though...why not just turn a pop-up camper into a pusher? :D
 

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
Yes, I stated in the original post that it is a mother to do a tight right turn. It skips over the pavement. It is doable and in reality probably no worse than say a stretch might be. At least as far as the swing needed to do a 90 degree right turn. but it does feel a little strange to have it skip. I got used to it though. The connection needs to be as rigid as possible
 

denbecr

New Member
Oct 21, 2008
19
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Illinois
With a 10hp though...why not just turn a pop-up camper into a pusher? :D
Since the 10 hp diesel propels the Metro to 50 mph, you COULD turn a pop-up into a traffic compatible pusher. Add a wheel to a tongue that steers it, something like a kid's Radio wagon but with one front wheel. The bike would then only have to support the weight of the tongue that also pivots up & down. Attach the tongue to the seatpost. I guess you could adapt motorcycle disc brakes to the camper's wheels. You'd have long cables to the throttle & brakes ! No reason not to place the engine on the tongue over the new wheel.

You would have to stuff your jeans to simulate huge leg muscles and "ghost pedal" to mislead the constabulary. scratg rotfl
 
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Luka

New Member
Aug 19, 2009
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Washington
Yes, I stated in the original post that it is a mother to do a tight right turn. It skips over the pavement. It is doable and in reality probably no worse than say a stretch might be. At least as far as the swing needed to do a 90 degree right turn. but it does feel a little strange to have it skip. I got used to it though. The connection needs to be as rigid as possible
Well dang if you didn't !

Sorry about that.

I was trying to read and digest too many things at the time I wrote that, and all I could think of was wondering just how much trouble the same sort of setup would give me, (300 pounds, plus bike), on a gravel road. And worse, a very steep switchback, on that same road...

Thank you for the response.